Diagnostic instrument for throwing a beam of light into the eye



lNVENTOR E. D. TILLYER E. D. TILLYER DIAGNOSTIC INSTRUMENT FOR THROWING A BEAM OF LIGHT INTO THE EYE Filed Nov. 5

April 3, 1928.

Patented Apr. 3, 1928.

' UNITED STATES PATENT OFFICE. v

EDGAR D. TILLYER, OF SOUTI-IBRIDGE, MASSACHUSETTS, ASSIGNOR TO AMERICAN OPTICAL COMPANY, OF SOUTl-IBRIDGE, MASSACHUSETTS, A VOLUNTARY ASSOCIA- TION OF MASSACHUSETTS.

DIAGNOSTIC INSTRUMENT FOR THB-OWING A. BEAM OF LIGHT INTO THE EYE.

Application filed November This invention relates to improvements in eye testing instruments and has particular reference to retinoscopes or other similar'instruments whereby the pupil of the pat-ients eye is illuminated by a beam of light and the observations made by the operator.

Prior to my invention, retinoscopes-have been provided with a reflecting mirror over the center of which is a small peep-hole of from 1 g to of an inch in diameter, which is much smaller than the pupil of the observers eye. This peep-hole breaks up the reflecting surface of the mirror and tends to cast a false shadow on the eye of the patient and unless the operator-is very skillful in us ing the device and in allowing for this false shadow, inaccurate refractions will result. Furthermore, in looking through this small opening, the operator is obliged to squint,

which causes a great strain on his eye, sufficient to cause injury to the busy refractionist. In those prior art devices using such a sight opening, the source of illumination has been made the basis of work rather than the pa- 7 tients eye and the returned image to the eye of the observer is larger than the pupil of the observers eye. With my invention,

I make the patients eye the basis of the work without any undue discomfort to the patient.

One of the principal objects of the invention is to provide a retinoscope wherein the maximum percentage of light from the patients eye is transmitted to the observers eye.

Another object of the invention is to provide such an instrument which will not cast a false shadow on the eye of the patient being examined.

A further object is to provide a device of this character which will be extremely simple in construction, eflicient in service, and an improvement in the art.

Other objects and advantages will be apparent from the following description taken in connection with the accompanying draw' ings wherein similar reference characters are used to designate corresponding parts throughout the several views.

In the drawings:

Figure 1 is a diagrammatic view illustrating my retinoscope in use.

Figure 2 is a vertical Sectional view 5, 1923. Serial No. 672,926.

through one form of retinoscope embodying my invention. o a

Figure 3 is a sectional View through another form of my invention. Figure f is a rear elevation of same. Referring now particularly to Figure2, I provide a retinoscope havinga tubular portion 10 wherein is mounted an illuminating bulb 11, the tube being open at its upper end and provided with a lens 12. Disposed between the lens 12 and the bulb 11 is a diaphragm 13 which is used to concentrate the light into a fine beam, and which may be secured within the tube in any suitable manner. The tube 10 is supported upon the usual handle member 14 which may, if desired, carry the battery or other suitable source of power for the light bulb 11.

Carried by the tube 10 is an upstanding plate 15 having mounted on its front side a reflector bracket 16 which carries the reflece tor ,17 which is the essence of my invention. In this form of the invention the reflector 17 is angularly disposed above the lensl2, preferably in such a way that the light rays from the tube 10 will impinge on the surface 1 i of the reflector 17 and be reflected therefrom at an angle of about My reflector is made of a piece of plain glass and has a nonmetallic reflecting surface which I accomplish preferably by producing a high polishon the front side of the reflector.

The reflector thus formed is entirel transparent and preferably has the maximum light transmitting properties. In line with the central portion of the reflectorthe plate 17 and the-bracket 16 are provided with a sight opening 18 which is preferably circular in shape and isof asize slightly larger than 9 the pupil of the average persons eye.

, In use, the operator holds this device up to one eye and sights throughthe opening 18 with the reflector 17 pointed towards the patient. The light from the bulb 11 is refiected by the member 17 to the eye of the patient and reflected back to the eye of the observer as is done in the ordinary type of retinoscope. Due to the fact that my reflector 17 has a continuous reflecting surface on its forward side there will be no false image cast upon the patients eye and be 17 having ahighly polished surface 19 on its front side and provided on its back with an opaque plate 20 having a peripheral flange 21 surrounding the edge of the reflector 17. The plate 20 has a center aper- V ture 22 which corresponds with the sightopening 18 of the other form hereinbefore described. A suitable handle member 23 is adapted to carry the plate 20' and its enclosed reflector 17.

In use, this second form ofthe invention has the source of light arranged behind the head of the patient, preferablyto one side or above the same and the retinoscope is shitably tilted by the operator to reflect the light from the source into the patients eye, thereupon the observer makes his usual examination through the opening 22.

The glass 17 has a reflecting factor m which is the ratio of the light reflected by i the mirror to thatjstriking the mirror v 1 and which increases witlrthe angle of inci; dence according to known lawsfbut which does not reach its maximum until nearly grazing incidence is a condition. Therefore, it will beeviden-t that in the reflecting surface there will be a certain amount of loss so that the reflected light beam I is equal to 1 m." (See Figure 1.) 7

The patient has a returned factor'K which is the" ratio of the light reflected by the eye to that received 'by it and which is known to those skilled in the art, so that the image reflected back'to the observer is less than More specificall I equals K I 1 mend the image I; which reaches the observer i'sf less than 1 because of the fact that there are cer tain losses in passin from thereflector l'i'. Clear gIassfmm which I prefer to make my reflector 17 has a tra nsmi ts rfhout' 92% or the lightstriking it, so

the observers eye, which is very desirable V as has been previously pointed out, There is no false shadow cast upon the patients eye because of the fact that the surf-ace of the reflector is continuous. From this it will be seen that I have produced a highly desirable andsimple retinscope which will he 'ecoiionii'eall'to manulaetui-e, e'flici'en't use and a general improvement in the art;

Another nios't' important advantage is that the eye of the patient; not daZz-led by an excess light as in other foi'insof retinoscopos since so much larger percentage of light from the patients eye reaches the observers eye. The efiioiency of a rctinoscope is measured biyrt'he per cent of amount of light leaving the patients eyewhich oanreach the-observefls eye it no obstruction intervenes. If

to and I reserve thel right to make such,

changes falling within the" scope of the appended claims without departing from the spirit of my invention. a

Iclaim: I Y

1; In a diagnostic instrument rorthrow ing abeam of light into a patientseye, a support having a sight opening larger than the pupil of the humaneye' anda transparent reflecting member secured to the sup 7 port in alignment with the said opening, the side of the reflectin member removed from the support being highly polished and having a continuous reflectlng surtace whereby thclight reflected from-the atients eyeiwil-l convey the whole *ini'age to-rt e'observer s eye Withoutshhdtw;

2.11mi diagnostic instrument for throwing a'beain of light into a patients zeyeya support having a sightopening of substantial ly the size of the pupi -1 of the-human eye and a transparent reflecting member secured to the support in alignment withlthe said opening, fiheside'ofthe reflecting men'i'ber removed from the support beinghigh ly polished and havin -a continuous reflecting surawe wherebyt e ilig'ht refleeted from the patients eye will convey thewwholewimage to the observers eye withoutshadow. V 

